1. Field of the Invention
The present invention relates to a device for regulating the air supply of an internal combustion engine supercharged by a turbo-compressor unit rotatably driven by the engine's exhaust. The invention applies particularly to controlled ignition engines running on gasoline or other vaporizable fuel for which the intake of air at the entrance to the combustion chambers of the engine can be choked by a regulator element, such as one or more butterfly valves, controlled by an accelerator linkage located downstream from the compressor.
2. Description of the Prior Art
One drawback of this arrangement appears upon acceleration from idle. The turbo-compressor rotor is turning at a relatively low speed during idle. To regain speed requires several seconds of acceleration under the effect of the still limited exhaust flow of the engine. At the instant the turbo-compressor rotor first begins to pick up speed, the compressor rotor, which is turning at low speed, acts to create a pressure loss in the engine's air supply circuit, instead of delivering a pressure boost. This further reduces the flow of air taken in by the accelerating engine, even though the engine's air supply butterfly valve is fully open. It is only after a considerable increase in the speed of the turbine that the air supply pressure of the engine will exceed the atmospheric pressure and thus create an appreciable increase in the flow of exhaust gas, enabling rapid acceleration of the turbo-compressor rotor to its maximal speed and assuring a clear pressure boost to the engine.